Ron Feutz feutz at wctc.net
Wed Jan 12 11:38:01 EST 2005

Thanks Jim,

Where can I buy the

At 09:01 AM 1/12/2005, you wrote:
>On Tue, 11 Jan 2005 22:12:21 -0600, Ron Feutz wrote:
> >I think the answer is big torroids on the incoming AC, CAT5 and phone lines
> >to the digital convertors.
> >
> > From reading the archives, 2" #73 torroids appear to be right.
>I've been doing considerable research on that, and can offer this advice. The
>Fair-Rite 2.4" O.D. toroids are listed in the catalog with #43, #78, and #61.
>I've also just received (and measured) samples of #31.
>For 160-40 meters, first choice would be 7 turns around #31 (if you can 
>find it),
>second choice would be 10-12 turns around #43. The advantage of #31 is 
>that it
>gives more attenuation over greater bandwidth and does it with fewer turns.
>The #78 material isn't very useful about about 4 MHz, and it takes 14 
>turns to
>get that high. The #61 material has far too high a Q to be broadband 
>enough to
>cover 160-40, and it would take more turns than you could wind. #73 is a nice
>material, but is used only for much smaller beads.
>Now, to prioritize which wiring should get the chokes first -- I would 
>look for
>obvious pin 1 problems and hit those first. If you want to go brute force, do
>them all. The advantage of this size of core is that you can get a lot of 
>through it, often without taking off connectors.
>BTW -- choking the Ethernet cable will also kill some of the common-mode 
>trash it
>radiates on the ham bands.
>Jim Brown  K9YC
>RFI mailing list
>RFI at contesting.com

Ron Feutz, KK9K
Air Communications of Central Wisconsin, Inc.
715-424-3050 days
715-423-7662 nights
715-572-3621 cell  

More information about the RFI mailing list